Recently, manufacturing designs have increasingly incorporated parts having free-form or complex geometries. Although parts having such geometries often replace parts having simpler geometries, there is still a need to verify the accuracy of parts having complex geometries for both fit and function.
Although evaluating the accuracy of manufactured parts having complex geometries is more difficult than inspection of their prismatic predecessors, the method of U.S. application Ser. No. 08/252,813, filed Jun. 2, 1994, now U.S. Pat. No. 5,442,572, provides an efficient and accurate method for verifying conformance of a manufactured part to its design specifications.
The method generates a color coded error map of the localized differences along the local surface normal of the master, or in any specified direction, between a part being inspected and the master by using high density point data modeling (HDPDM) techniques. Such error maps allows the user to evaluate the quality of free-form parts and diagnose the manufacturing deficiencies quickly and accurately. The method is capable of comparing two distinct physical parts, two math/cad models, or a physical part and a cad model.
The technology may also be applied to determine how well two mating parts fit when they are brought together such as stamping or molding dies. Unfortunately, the accurate alignment of two parts, which is necessary for proper comparison, is often difficult to achieve.
The task of accurately aligning data representing two parts presents a problem for virtually every computerized comparison method. A typical mathematical approach to the alignment problem incorporates a least squares analysis. This approach has not been effective in many situations.